Apparatus and method for modifying a combustor nozzle

ABSTRACT

A combustor nozzle includes a nozzle body that defines a cavity. An orifice in the nozzle body provides fluid communication from the cavity through the nozzle body. A movable barrier proximate to the orifice has a first position in which the movable barrier at least partially obstructs the orifice. A method for supplying fuel to a combustor includes flowing fuel through an orifice in a nozzle, determining a reactivity of the fuel, and adjusting an effective cross sectional area of the orifice based on the reactivity of the fuel.

FIELD OF THE INVENTION

The present invention generally involves an apparatus and method formodifying a combustor nozzle. In particular, embodiments of the presentinvention include a nozzle that can be adjusted to operate with fuelshaving different reactivity levels.

BACKGROUND OF THE INVENTION

Combustors are widely used in commercial operations. For example, atypical gas turbine includes a compressor that supplies a compressedworking fluid to at least one combustor. The combustor mixes fuel withthe compressed working fluid and ignites the mixture to producecombustion gases having a high temperature and pressure. The combustiongases exit the combustor and flow to a turbine where they expand toproduce work.

Various fuels may be supplied to the combustor for combustion. Forexample, the combustor may be designed to operate using blast furnacegas, coke oven gas, natural gas, vaporized liquefied natural gas (LNG),propane, hydrogen, or combinations thereof. Each fuel type generally hasa different reactivity for combustion. In addition, the reactivity mayvary among fuels of the same type, depending on various factors such asthe fuel supplier, purity, temperature, addition of diluents, etc.Changes in the fuel may change the operation and/or performance ofvarious components in the gas turbine. For example, a change in thereactivity of the fuel may change the pressure, temperature, and outputof the combustor. Therefore, it may be desirable to adjust thecombustor, and specifically the nozzles in the combustor, to accommodatefuels having different reactivity levels.

Various efforts have been made to design and operate combustors withdifferent reactivity fuels. For example, the operating limits of thecombustors may be adjusted based on the reactivity of the fuel. However,this solution may result in reduced operating limits for the combustorsor other equipment associated with the gas turbine. Another solution foroperating combustors with different reactivity fuels is to shut down thecombustor and replace one or more nozzles with substitute nozzles havingdifferent sized fuel orifices. However, this method requiresinterruption of the service provided by the gas turbine as well as aninventory of substitute nozzles. Interruption of the service provided bythe gas turbine obviously results in unplanned and unwanted outages, andthe inventory of substitute nozzles increases the operating costs forthe gas turbine. As a result, an improved nozzle that can be adjusted tooperate with different reactivity fuels would be desirable.

BRIEF DESCRIPTION OF THE INVENTION

Aspects and advantages of the invention are set forth below in thefollowing description, or may be obvious from the description, or may belearned through practice of the invention.

One embodiment of the present invention is a combustor nozzle thatincludes a nozzle body that defines a cavity. An orifice in the nozzlebody provides fluid communication from the cavity through the nozzlebody. A movable barrier proximate to the orifice has a first position inwhich the movable barrier at least partially obstructs the orifice.

Another embodiment of the present invention is a combustor nozzle thatincludes a nozzle body that defines a cavity. An orifice in the nozzlebody provides fluid communication from the cavity through the nozzlebody. A removable insert in the orifice reduces effective crosssectional area of the orifice.

The present invention also includes a method for supplying fuel to acombustor. The method includes flowing fuel through an orifice in anozzle, determining a reactivity of the fuel, and adjusting an effectivecross sectional area of the orifice based on the reactivity of the fuel.

Those of ordinary skill in the art will better appreciate the featuresand aspects of such embodiments, and others, upon review of thespecification.

BRIEF DESCRIPTION OF THE DRAWINGS

A full and enabling disclosure of the present invention, including thebest mode thereof to one skilled in the art, is set forth moreparticularly in the remainder of the specification, including referenceto the accompanying figures, in which:

FIG. 1 is a simplified cross-section of a combustor known in the art;

FIG. 2 is a simplified cross-section of a nozzle according to oneembodiment of the present invention;

FIG. 3 is a simplified cross-section of a nozzle according to analternate embodiment of the present invention;

FIG. 4 is a perspective view of a removable insert according to oneembodiment of the present invention;

FIG. 5 is a perspective view of a removable insert according to a secondembodiment of the present invention; and

FIG. 6 is a perspective view of a removable insert according to a thirdembodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Reference will now be made in detail to present embodiments of theinvention, one or more examples of which are illustrated in theaccompanying drawings. The detailed description uses numerical andletter designations to refer to features in the drawings. Like orsimilar designations in the drawings and description have been used torefer to like or similar parts of the invention.

Each example is provided by way of explanation of the invention, notlimitation of the invention. In fact, it will be apparent to thoseskilled in the art that modifications and variations can be made in thepresent invention without departing from the scope or spirit thereof.For instance, features illustrated or described as part of oneembodiment may be used on another embodiment to yield a still furtherembodiment. Thus, it is intended that the present invention covers suchmodifications and variations as come within the scope of the appendedclaims and their equivalents.

Various embodiments of the present invention provide a nozzle for acombustor that may be used with different reactivity fuels. The nozzlegenerally includes one or more orifices for flowing fuel into acombustion chamber, and the cross sectional area of the one or moreorifices may be increased or decreased according to the reactivity ofthe fuel. As a result, the nozzle may be adjusted to be used with fuelshaving different reactivity levels.

FIG. 1 provides a simplified cross-section of a combustor 10 within thescope of the present invention. Although the combustor 10 illustrated inFIG. 1 is suitable for use in a gas turbine system, one of ordinaryskill in the art will readily appreciate that the embodiments of thepresent invention described herein are not limited to a combustor usedin a gas turbine system, unless specifically recited in the claims. Acasing 12 may surround the combustor 10 to contain a compressed workingfluid. Nozzles may be arranged in an end cover 16, for example, withprimary nozzles 18 radially arranged around a secondary nozzle 20, asshown in FIG. 1. A liner 22 downstream of the nozzles 18, 20 may definean upstream chamber 24 and a downstream chamber 26 separated by a throat28. The compressed working fluid may flow between the casing 12 and theliner 22 to the nozzles 18, 20. The nozzles 18, 20 mix fuel with thecompressed working fluid, and the mixture flows from the nozzles 18, 20into the upstream 24 and downstream 26 chambers where combustion occurs.

FIG. 2 provides a simplified cross-section of a nozzle 30 installed inthe end cover 16 of the combustor 10 according to one embodiment of thepresent invention. As shown, the nozzle 30 generally includes a nozzlebody 32 that defines a cavity 34 inside the nozzle 30 and one or moreorifices 36 in the nozzle body 32 that provide fluid communication fromthe cavity 34 through the nozzle body 32. The nozzle 30 may furtherinclude a shroud 38 surrounding the nozzle body 32 with one or moreswirler vanes 40 radially arranged between the shroud 38 and the nozzlebody 32. A supply of fuel 42 connected to the nozzle 30 supplies fuel tothe cavity 34. The fuel then flows through the one or more orifices 36,and the swirler vanes 40, if present, swirl the fuel entering theupstream chamber 24 prior to combustion.

As shown in FIG. 2, the nozzle may further include one or more movablebarriers 44 proximate to the one or more orifices 36. The movablebarrier 44 generally includes a distal end 46 having any geometricshape. For example, the distal end 46 may comprise a cylinder, circle,square, triangle, or other geometric shape. The movable barrier 44 maybe located completely inside the cavity 34, as shown in FIG. 2. Inalternate embodiments, the movable barrier 44 may be located partiallyinside the cavity 34, with the distal end 46 extending through theorifice 36.

The movable barrier 44 has a first position and a second position. Inthe first position, the distal end 46 of the movable barrier 44 iscloser to the orifice 36 to obstruct the orifice 36 and/or reduce theeffective cross sectional area of the orifice 36. As used herein, theeffective cross sectional area of the orifice 36 is the total areathrough which the fuel they flow from the cavity 34 into the upstreamchamber 24. For example, in the first position, the distal end 46 of themovable barrier 44 may be close enough to the orifice 36, or even insidethe orifice 36, so as to reduce the effective cross sectional area ofthe orifice 36, thereby reducing the flow rate of fuel from the cavity34, through the orifice 36, and into the combustion chamber 24. In thesecond position, the distal end 46 of the movable barrier 44 may befurther from the orifice 36 so as to increase the effective crosssectional area of the orifice 36. For example, in the second position,the distal end 46 of the movable barrier 44 may be far enough from theorifice 36 so that the effective cross sectional area of the orifice 36is maximized, thereby increasing the flow rate of fuel from the cavity34, through the orifice 36, and into the combustion chamber 24.

The movable barrier 44 may be connected to a hub 48 inside the cavity 34and may include means for moving the movable barrier 44. For example, asshown in FIG. 2, each distal end 46 may be connected by a rod 50 orpiston to the hub 48. Each rod 50 or piston may include internal orexternal threads 52 that provide a threaded engagement between each rod50 and the hub 48. In this manner, the threaded engagement between eachrod 50 and the hub 48 provides the means for moving the movable barrier44. Alternately, or in addition, the means for moving the movablebarrier 44 may comprise a pneumatic or hydraulic supply 54 connected tothe hub 48. Air or another fluid may thus be supplied to the hub 48 topneumatically or hydraulically extend or retract each rod 50 withrespect to the hub 48. In still further embodiments, the means formoving the movable barrier 44 may comprise any articulated, threaded,ratcheted, hinged, or other mechanical structure known in the art forreciprocating movement.

The embodiment of the nozzle 30 shown and described with respect to FIG.2 thus provides several advantages over existing designs. For example, acustomer may determine a reactivity of the fuel and readily adjust theflow rate of fuel through the nozzle 30 by adjusting the position of themovable barrier 44. In this manner, the customer may adjust theeffective cross sectional area of the orifices 36 in the nozzle 30 basedon the reactivity of the fuel. As a result, the customer does not haveto maintain an inventory of substitute nozzles and may instead switchbetween fuel types or different reactivity fuels without requiring anunscheduled or unwanted shutdown to replace the nozzle. In addition, themovable barrier 44 allows the customer to slightly adjust the positionof the movable barrier 44 during steady-state operations to achieve adesired combustor output.

FIG. 3 shows is a simplified cross-section of a nozzle 60 according toan alternate embodiment of the present invention. As shown, the nozzle60 generally includes a nozzle body 62 that defines a cavity 64 insidethe nozzle 60 and one or more orifices 66 in the nozzle body 62 thatprovide fluid communication from the cavity 64 through the nozzle body62. The nozzle 60 may further include a shroud 68 surrounding the nozzlebody 62 with one or more swirler vanes 70 radially arranged between theshroud 68 and the nozzle body 62. A supply of fuel 72 connected to thenozzle 60 supplies fuel to the cavity 64. The fuel than flows throughthe one or more orifices 66, and the swirler vanes 70, if present, swirlthe fuel entering the combustion chamber 24 prior to combustion.

As shown in FIG. 3, the nozzle 60 may further include one or moreremovable inserts 74 in one or more orifices 66. The removable inserts74 may have various internal diameters corresponding to variousreactivity levels in the fuel. In particular embodiments, the removableinserts 74 may comprise a solid insert that serves as a plug tocompletely block fuel flow through an individual orifice 66. In thismanner, the removable inserts 74 may be installed in each orifice 66 ora subset of orifices 66 to reduce the effective cross sectional area ofthe orifices 66, thereby reducing the flow rate of fuel from the cavity64, through the orifices 66, and into the combustion chamber 24. Whendesired, the removable inserts 74 may be removed from the orifices 66 sothat the effective cross sectional area of the orifices 66 is maximized,thereby increasing the flow rate of fuel from the cavity 64, through theorifices 66, and into the combustion chamber 24.

FIGS. 4, 5, and 6 provide perspective views of removable insertsaccording to alternate embodiments of the present invention. Forexample, the removable insert 74 shown in FIG. 4 includes a smooth innersurface 76 and a threaded outer surface 78 that allows the removableinsert 74 may be threaded into or out of the orifice 66. The removableinsert 80 shown in FIG. 5 includes a smooth outer surface 82 and agrooved or rifled inner surface 84. The removable insert 86 shown inFIG. 6 similarly includes a smooth outer surface 82 with turbulators 88on the inner surface. In this manner, the removable inserts 80, 86 shownin FIG. 5 or 6 may be press fit into the orifice 66, and the groovedinner surface 84 or turbulators 88 on the inner surface enhancesswirling, acceleration, and/or mixing of fuel flowing through theremovable inserts 80, 86.

The embodiment of the nozzle 60 shown and described with respect toFIGS. 3, 4, 5, and 6 thus provides several advantages over existingdesigns. For example, a customer may determine a reactivity of the fueland readily adjust the flow rate of fuel through the nozzle 60 byinstalling or removing one or more removable inserts 74 from one or moreorifices 66. In this manner, the customer may adjust the effective crosssectional area of the orifices 66 in the nozzle 60 based on thereactivity of the fuel. As a result, the customer does not have tomaintain an inventory of substitute nozzles and may instead switchbetween fuel types or fuels having different reactivity levels withoutreplacing the nozzle.

This written description uses examples to disclose the invention,including the best mode, and also to enable any person skilled in theart to practice the invention, including making and using any devices orsystems and performing any incorporated methods. The patentable scope ofthe invention is defined by the claims, and may include other examplesthat occur to those skilled in the art. Such other and examples areintended to be within the scope of the claims if they include structuralelements that do not differ from the literal language of the claims, orif they include equivalent structural elements with insubstantialdifferences from the literal languages of the claims.

1. A combustor nozzle comprising: a. a nozzle body, wherein the nozzlebody defines a cavity; b. an orifice in the nozzle body, wherein theorifice provides fluid communication from the cavity through the nozzlebody; and c. a movable barrier proximate to the orifice, wherein themovable barrier has a first position in which the movable barrier atleast partially obstructs the orifice.
 2. The combustor nozzle as inclaim 1, further comprising means for moving the movable barrier.
 3. Thecombustor nozzle as in claim 1, wherein the movable barrier is insidethe cavity.
 4. The combustor nozzle as in claim 1, wherein the movablebarrier reduces an effective cross sectional area of the orifice in thefirst position.
 5. The combustor nozzle as in claim 1, wherein themovable barrier has a second position in which the movable barrierincreases an effective cross sectional area of the orifice.
 6. Thecombustor nozzle as in claim 1, further comprising a plurality oforifices in the nozzle body and a plurality of movable barriersproximate to the plurality of orifices, wherein the plurality of movablebarriers have a first position that at least partially obstructs theplurality of orifices.
 7. The combustor nozzle as in claim 1, furthercomprising a hub inside the cavity, wherein the barrier is connected tothe hub.
 8. The combustor nozzle as in claim 7, wherein the movablebarrier is in threaded engagement with the hub.
 9. A combustor nozzlecomprising: a. a nozzle body, wherein the nozzle body defines a cavity;b. an orifice in the nozzle body, wherein the orifice provides fluidcommunication from the cavity through the nozzle body; and c. aremovable insert in the orifice, wherein the removable insert reduceseffective cross sectional area of the orifice.
 10. The combustor nozzleas in claim 9, wherein the removable insert as in threaded engagementwith the orifice.
 11. The combustor nozzle as in claim 9, wherein theremovable insert is press fit into the orifice.
 12. The combustor nozzleas in claim 9, wherein the removable insert has a grooved internalsurface.
 13. The combustor nozzle as in claim 9, wherein the removableinsert has an internal surface and further comprising turbulators on theinternal surface.
 14. The combustor nozzle as in claim 9, furthercomprising a plurality of orifices in the nozzle body, wherein each ofthe plurality of orifices provides fluid communication from the cavitythrough the nozzle body.
 15. The combustor nozzle as in claim 14,further comprising the removable insert in each of the plurality oforifices, wherein each removable insert reduces an effective crosssectional area of the orifice therein.
 16. A method for supplying fuelto a combustor comprising: a. flowing fuel through an orifice in anozzle; b. determining a reactivity of the fuel; c. adjusting aneffective cross sectional area of the orifice based on the reactivity ofthe fuel.
 17. The method as in claim 16, further comprising reducing theeffective cross sectional area of the orifice.
 18. The method as inclaim 16, further comprising installing an insert into the orifice. 19.The method as in claim 16, further comprising removing an insert fromthe orifice.
 20. The method as in claim 16, further comprising flowingfuel through a plurality of orifices in the nozzle and adjusting aneffective cross sectional area of the plurality of orifices based on thereactivity of the fuel.